Drive means for compressors or the like



IJan. 4, 1949. F. w. EDWARDS 2,457,880

DRIVE IEANS FOR COIIPRESSORS 0R THE LIKE Filed July 51, 1944 INVENTOR.

)7a/Illa? M1/Ward@ BY E mm Patented Jan. 4, 1949 DRIVE MEANS FOB COMPBESSOBS OR THE LIKE Franklin W. Edwards, Detroit, Mich., allignor to Chrysler. Corporation, Highland Park, Mich., a

corporation of Delaware Application July 31, 1944, Serial No. 547,480

1 Claim. 1

This invention relates to driving mechanism for pumps, compressors, or the like. It is useful in any instance where it is necessary to drive a sealed or gas tight mechanism from an external power source.

Specifically, the invention is applied in the present instance to a compressor of the sealed type, such as is used in refrigerating apparatus.

Heretofore, these compressors have given considerable difllculty due to gas leakage around the bearing of the driving shaft. While expensive rotary seals are commonly used, gas does escape which requires replacement at regular intervals to maintain proper pressure.

It is the principal object of my invention to provide an improved driving connection between the compressor driving shaft and the power source which is one hundred per cent gas tight and which does not require the use of shaft seals, bellows, fluid seals, or the like.

Other objects and advantages will be apparent from the following description. In the drawing which accompanies the description,

Fig. 1 is an elevational sectional view of my improved compressor driving mechanism.

2 insulating material 26 and are respectively connected with opposite ends of the coil I1 by means of conductors 2i, 22.

Provided on the portion I6 adjacent the iield coil Il are teeth 23, two sets being provided, one on each side of the coil. The purpose of these teeth will be presently made clear.

The mechanism just described which is carried by the shaft II constitutes one element of an electromagnetic coupling of the eddy-current type. The other element is formed by an annular member 24 which has internal ring portions 25 disposed radially adjacent the magnetic casing portions I4, which in turn, are radially aligned with the teeth 23.

The member 24 is rotatably carried by a bearing 26 on a hub 21 formed on the end plate I5. Formed integrally on the number 24 is a pulley portion 26 which is adapted to receive a V-belt 29. The latter is driven by a source of power such as an electric motor, engine or the like.

When the field coil I1 is energized magnetic flux surrounds the coil and travels in a circular path through the teeth 23, the magnetic casing por- Figs. 2 and 3 are similar views oi modified forms of the invention.

Referring to Fig. 1 for the moment, it will be seen that I have shown a casing I which is adapted to house a compressor having an operating shaft I I. Inasmuch as the compressor details form no part of the invention, I have omitted them for the sake of clarity. It is believed sulficlent to state that the shaft II is geared to or drives directly the pump, compressor or the like and that the driven mechanism is enclosed in a hermetically sealed casing I0.

The casing III has an annular extension I2 which has a number of annular non-magnetic sections I3 welded or otherwise secured to annular sections I4 of magnetic material. The joints between the alternate sections of magnetic and non-magnetic material are hermetically healed and an end plate I5 is fixed on the end of the section with a fluid and gas tight joint.

The drive shaft II has an enlarged section I6 of ferrous material which carries a field coil I1, mounted as shown. The coil Il is energized through a pair of conductors I8 which are adapted to be connected to a source of electric power, such as a storage battery. The conductors are connected to a pair of brushes I9 which are mounted in the wall of casing Ill and which bear on slip rings carried by the enlarged portion I6. The slip rings are carried in suitable tions I4 and the member 24. Rotation of the member 24 by the power source causes alternate regions of high and low flux density to be set up in the member 24 because of the teeth 23, the flux from the coil tending of course to travel through the teeth where the air gap is shortest. These alternating regions of high and low flux density generate eddy currents in the members I6 and 24 which set up magnetic forces tending to oppose relative rotation between the members. The member I6 will therefore tend to rotate in unison with the driving element 24.

Because of the inherent "slip" between the elements I6 and 24 due to the unavoidable losses, the member I6 will never catch up with the driving element 24. However, the slip is relatively slight in a well designed coupling and the loss in drive efllciency negligible. The annular casing sections I4 of magnetic material decrease the effective air gap between the teeth 23 and portions 25, and the non-magnetic casing sections I4 act to confine the flux travel to a well defined path, all of which materially enhances the overall operating efllciency of the drive.

In Fig. 2, I have illustrated a modification of the above described arrangement which has advantages over the Fig. 1 form in certain installations because, among other things, no externalinternal electrical connection is required. In Fig. 2, the brushes I9 are carried on an externally mounted support 30 and the fleld coil I1 is carried by the driving element Il' of the coupling instead of the driven element I9' thereof. Likewise. the outer element Il' carries the slip rings 2l' which supply the coil through conductors 2|', Il.

The teeth 2l' are positioned on the outer member, but the ilux path is similar to that in Fig. 1. vIn Fig. 2, the non-magnetic section il', the magnetic section il and the end plate Il' are all secured together and to the main casing Il by means of a plurality of studs Il ci brass or similar non-magnetic material. The studs ll are drawn up tight to provide a gas tight Joint and if necessary, some form of adhesive sealing compound may be used to seal the joints between sections.

In Fig. 3, the coil I1" is carried by the casing itself. the teeth 23" being disposed on the driven member Il". The teeth could be located on the driving member 2l" if desired. The operation o! the Fig. 3 coupling is identical with that of Fils. 1 and 2.

The Fig. 3 form is preferable in many installations because ot its simplicity, particularly with 4 invention, I wish it understood that it is not intended to limit the scope oi' the invention in its broader aspects except as sot forth in the appended claim.

I claim:

In an electromagnetic drive means for a compressor or the like. a hermetically sealed casing for the compressor having a. cylindrical portion extending therefrom constructed ,of alternately disposed rings of magnetic and non-magnetic material; an end plate for closing the end of the said extending casing portion, and a plurality of non-magnetic studs disposed axially of said rings for securing said rings and plate together in fluid tight relation.

W. EDWARDS.

REFERENCES CITED The following references are of record in the ille of this patent:

Y UNITED STATES PATENTS Number Name Date '762,620 Eastwood June 14, 1904 1,221,295 Dopkins Apr. 3, 1917 1,271,401 Weydell July 2, 1918 1,308,435 Maine July l, 1919 1,422,243 VanNorden July 11, 1922 1,911,960 Lipman May 30, 1933 1,917,760 Geiger July 11, 1933 2,131,035 Deechlyn Sept. 27, 1938 

